Download presentation
Presentation is loading. Please wait.
Published byRandell Lewis Modified over 9 years ago
1
Lethal and Sub-lethal Effects of Resmethrin on Nontargeted Species Meredith Blank 2006
2
Background Resmethrin- synthetic pyrethroid made from chrysanthemum flowers http://www.beyondblossoms.com/blog/wp- content/chrysanthemums_01.jpg
3
Background Resmethrin—contact poison that quickly penetrates the nerve system of the insect Sprayed throughout Twin Cities by MMCD to control mosquito population
4
Societal Implications Increased prevalence of West Nile Virus= MMCD sprays resmethrin more to control mosquito populations Effects on many nontargeted species not yet known
5
Purpose To determine effects of resmethrin on monarch butterflies (Danaus plexippus), milkweed bugs (Lygaeus kalmii),and houseflies (Musca Domestica) Acertainslantoflight.blogspot.comtroyb.com
6
Previous Studies Dr. Oberhauser and Sara Brinda (2003- 04) The Effects of Mosquito-Control Applications of Permethrin on Monarch Butterfly (Danaus plexippus) Larvae Rosemary Lelich (2004-05) Effects of Resmethrin Spray on Monarch Butterflies (Danaus plexippus)
7
Methods: Preparing Monarch Larvae for Spraying Treatment TypeStudy Procedure 0-day2 nd and 4 th instar larvae were sprayed directly with resmethrin 1-day2 nd and 4 th instar larvae were fed leaves from sprayed plants one day after spraying 2-day2 nd and 4 th instar larvae were fed leaves from sprayed plants two days after spraying 4-day2 nd and 4 th instar larvae were fed leaves from sprayed plants four days after spraying
8
Methods: Spray Set-up National Sports Center, Blaine, Minnesota
9
Methods: Spray Transect Transect A 3 mw plants and 1 mw plant w/ larvae +2 cages 3 mw plants and 1 mw plant w/ larvae +2 cages 3 mw plants and 1 mw plant w/ larvae +2 cages Transect B 3 mw plants and 1 mw plant w/ larvae+2 cages 170 m 120 m 75 m 30 m 15 m Spray Path 15 m Downwind Upwind Distance from Spray Path
10
Methods: Spray Transect Transect A 3 mw plants and 1 mw plant w/ larvae +2 cages 3 mw plants and 1 mw plant w/ larvae +2 cages 3 mw plants and 1 mw plant w/ larvae +2 cages Transect B 3 mw plants and 1 mw plant w/ larvae+2 cages 170 m 120 m 75 m 30 m 15 m Spray Path 15 m Downwind Upwind Distance from Spray Path
11
Goals and Hypotheses Goal 1: See if monarch larvae exposed closer to spray path would have a lower survival rate Hypothesis 1: Monarch larvae exposed to resmethrin at closer distances to the spray would have a lower survival rate
12
Results on Hypothesis 1
13
Goals and Hypotheses Goal 2: See if monarchs exposed to resmethrin would emerge as smaller adults Hypothesis 2: Monarch larvae exposed to resmethrin would become smaller adults
14
Results on Hypothesis 2
15
Goals and Hypotheses Goal 3: See if there were lethal effects on milkweed bugs and houseflies Hypothesis 3: Milkweed bugs and houseflies exposed to resmethrin would have a lower survival rate
16
Results on Hypothesis 3 Location Number of Cages Mean Survival Standard Error Transect A60.96670.0333 Transect B60.91110.0588 Control 110.4000 Control 210.8000 Control 311.000 Table 3: Mean Survival of Milkweed Bugs; linear regression t- test gave p = 0.33
17
Results on Hypothesis 3 Location Numbers of Cages Mean Survival Standard Error Transect A60.19300.0797 Transect B60.20800.0408 Control 110.2000 Control 210.0000 Control 310.6250 Table 4: Mean Survival of House Flies; linear regression t-test gave p = 0.26
18
Goals and Hypotheses Goal 4: See how long after spraying resmethrin would affect monarch butterflies Hypothesis 4: Monarch larvae directly exposed to resmethrin would have a lower survival rate than monarch larvae fed resmethrin-sprayed plants 1, 2, or 4 days later
19
Results on Hypothesis 4 Treatment TypeMean Survival 0-day0.6790 1-day0.7333 2-day0.8019 4-day0.9000 Table 5: Mean Survival Dependent on Day Exposed A linear regression t-test gave p-value = 0.0022
20
Conclusion Only the hypothesis that the days since spraying increased monarch larvae survival rate increased was accepted (p = 0.0022, using a significance level of p = 0.05)
21
Conclusion Monarchs sprayed with resmethrin did not have smaller masses (p = 0.21) Resmethrin did not have lethal effects on milkweed bugs (p = 0.33) Resmethrin did not have lethal effects on houseflies (p = 0.26) Survival rate did not increase as distance from spray path increased (p = 0.16)
22
Future Studies Test at more variable wind speeds and different summer temperature conditions Study other beneficial non-targeted species
23
Acknowledgments Dr. Oberhauser University of Minnesota monarch lab Ms. Fruen and Team Research
24
Lethal and Sub-lethal Effects of Resmethrin on Nontargeted Species Meredith Blank 2006
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.